The United Nations is calling on all parties in the Afghan conflict to facilitate health workers in conducting Monday’s urgent polio vaccination campaign in a volatile southern district with the highest number of polio virus cases of any district in the world.

U.N. Humanitarian Coordinator Toby Lanzer warned Sunday the situation in Shahwalikot district in Kandahar province puts hundreds of thousands of children at risk. He said a polio vaccination campaign throughout the district is more urgent than ever

Afghan officials last week reported a new case of wild polio virus, raising the number of cases in Kandahar to five and the nationwide total to 12 in 2017.

Afghan authorities with support from UNICEF and WHO are to vaccinate thousands of children in Shahwalikot starting Monday.

“The outbreak of polio in Shahwalikot means that Afghanistan remains one of only three countries in the world that is still polio-endemic and polio eradication is at risk globally,” Lanzer noted.

“I call on the authorities and all people with influence, including the leaders of the communities in Shahwalikot, to ensure that this polio vaccination campaign takes place by helping health workers, facilitating their task and protecting them and their supplies so that all children are protected against polio.”

Shahwalikot has been the scene of deadly clashes between Afghan security forces and Taliban insurgents. Southern Afghan provinces, including Kandahar, have been hub of insurgent activities.

Lanzer said that International humanitarian law stipulates clear responsibilities for all warring sides to facilitate the anti-polio drive.

“Together, with the support of all actors on the ground, we can help Afghans rid themselves once and for all of this terrible disease,” emphasized the U.N. Humanitarian Coordinator.

Afghanistan and Pakistan officially are now the only two nations across the globe to have reported wild polio virus cases so far this year, though the numbers of cases have dipped to historic lows. Pakistani authorities have reported six cases so far in 2017.

Nigeria is the third country in the world with ongoing wild polio-virus transmission, but so far this year no new cases have been reported.